1. Field of the Invention
The present invention relates to a linear motor.
2. Description of the Related Art
Linear motors have been utilized in a wide field of office automation equipment such as copying machines, image scanners and printers, factory automation equipment such as X-Y tables and object transporting devices, and optical equipment such as cameras.
For example, Japanese Laid-Open Patent Publication No. 57-52365 (1982) has proposed a linear motor, which includes a stationary field magnet having a plurality of alternately arranged magnetic poles of N- and S-poles, and a movable armature coil opposed to the field magnet with a gap therebetween. A plane of a central opening of the armature coil is opposed parallel to the field magnet.
Also, Japanese Laid-Open Patent Publication No. 59-6767 (1984) has proposed a structure of a linear motor in which two stationary field magnets each having a plurality of magnetic poles of N- and S-poles arranged alternately are opposed to each other with a gap therebetween, and a movable armature coil is disposed at the gap. In this example, a plane of a central opening of the armature coil is perpendicular to the moving direction of the armature coil.
However, in the linear motor taught by Japanese Laid-Open Patent Publication No. 57-52365, a conductor portion of the armature coil, which is parallel to the lengthwise direction of the field magnet, forms a useless portion which does not contribute to generation of a driving force, resulting in a low efficiency.
The linear motor taught by Japanese Laid-Open Patent Publication No. 59-6767 can produce a much higher driving force than the linear motor disclosed in Japanese Laid-Open Patent Publication No. 57-52365, but suffers from such a problem that fine adjustment of a positional relation between the two magnets is required because the two field magnets are independent of each other.